Hah! This is Why Touya is a Slytherin!
Enter the "Eternal Rival"


Hikaru can't be anything other than Gryffindor. It doesn't work any other way. Ravenclaw is laughable, as is Slytherin... and though he does have his Hufflepuff-ish moments, like when he thought he could give up go to get Sai back (hah! silly boy), those moments are cancelled out by his overpowering urge to be Touya's rival.

So if Hikaru is Gryffindor, then his "eternal rival" *must* be a Slytherin. ^^ It's logic.

Touya